During emergency situations where the transfer of crew or other objects is necessary while in warp, the warp fields of two vessels may be brought into contact with each other and merge to form one, provided both ships remain motionless relative to each other and at the same warp velocity. (ENT: "Divergence")

Several displays in engineering on the Enterprise-D show radiating lines emitting from the warp nacelles. These lines are tightly spaced in the front of the saucer while widely space at the rear, to the point of another whole ship length. (TNG)

According to the Star Trek: The Next Generation Technical Manual, the space-time continuum distortion based propulsive effect of a warp field is created by nesting several layers of warp field energy together, with each new layer exerting force against its outermost neighbor. The cumulative effect of this force results in the massive subspace field distortion that allows the ship to reach faster than light speeds. (p.54) The shape of the warp field produces the propulsive effect. (p.64) The forward lobe of the field is created with a frequency offset to create the field shape asymmetry required to drive the ship forward. (p.65)